Apparatus and method for washing alignment film printing mask and method for fabricating a liquid crystal display device

ABSTRACT

The present invention relates to an alignment film printing mask, and more particularly, to a jig for an alignment film printing mask. A jig according to the present invention includes a plurality of supporting members each having at least one bent portion, arranged at regular intervals along a width direction of the alignment film printing mask for supporting the alignment film printing mask, at l one connection member for connecting the supporting members, and fastening units for securing the alignment film printing mask supported by the supporting members.

This application claims the benefit of Korean Patent Application No.2005-53119, filed on Jun. 20, 2005, which is hereby incorporated byreference for all purposes as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an apparatus for washing an alignmentfilm printing mask and a method for fabricating a display device usingthe same, and more particularly, to a jig for washing an alignment filmprinting mask.

2. Discussion of the Related Art

Owing to advantages of low voltage driving, full color reproduction,light/thin/short/small configuration, a low power consumption, and soon, liquid crystal display devices have become widely applied toelectronic devices ranging from watches, calculators, notebookcomputers, to PDAs, TVs, cellular phones, monitors for air planes,monitors for PCs, and so on.

In order to use the liquid crystal display devices, it is required toorient liquid crystal molecules in a particular direction. To do so, anorganic polymer film called as an alignment film is formed on an ITOelectrode. The alignment film is formed by coating a liquid raw materialof the alignment film, for example, polyamic acid, soluble polyimide, orthe like, on a substrate, polyimidizing (or curing) the liquid rawmaterial, and rubbing the cured polyimide. That is, the liquid rawmaterial of the alignment film is printed on a upper surface of thesubstrate with an alignment film printing apparatus, and the liquid rawmaterial of the alignment film is heated to a temperature in a range of60° C.˜ 80° C. to primarily cure the liquid raw material, and is thenheated to a temperature in a range of 80° C.˜ 200° C. to secondarilycure the liquid raw material. Thereafter, the alignment film is formedby rubbing the surface of the raw material of the alignment film or bydirecting a beam of light onto it.

The alignment film is generally printed on either the substrate having aTFT pattern formed thereon or the substrate having a color filterpattern formed thereon using three rolls of a doctor roll, an aniloxroll and a printing roll, and an alignment film printing mask(hereinafter referred to as “mask”). The mask is generally constructedof a rubber plate (APR “Asahi Kasei Photosensitive Resin” rubber plate)having a predetermined pattern with openings. When the mask isrepeatedly used, polyimide (PI) used during the formation of thealignment film gradually accumulates at the openings. Therefore, it isrequired to wash the mask at appropriate intervals to remove the remainsof polyimide from the openings. A mask washing apparatus is separatelyused to do so.

The mask washing apparatus is provided with a washing tank filled withN-Methyl Pyrrolidone (NMP) liquid and a jig for holding the mask. Theheight of the washing tank is generally greater than the height of themask. The mask held by the jig is introduced into the washing tank.

Recently, as the size of the liquid crystal display devices has becomelarger, the size of the mask has become larger. Thus, the size of thejig and the height of the washing tank are required to become larger towash the large-size mask. Due to this trend, the consumption of NMP forwashing the mask is sharply increased, which increases the fabricationcost.

In addition, because the recent mask has a height in a range of2000˜3000 mm, a height of a clean room storing the production equipmentis required to be in a range of 5000˜6000 mm to introduce the mask intothe washing tank. As a result, a separate clean room space is requiredto install the mask washing apparatus, which further increases thefabrication cost.

Moreover, because the jig holding the mask is taken out of the washingtank after a predetermined time period in a series of washing steps, thewashing process is not effective. Also, the remains of NMP on the maskimpair the printing performance of the alignment film mask.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a jig for washing analignment film printing mask and a method for fabricating a displaydevice that substantially obviate one or more problems due tolimitations and disadvantages of the related art.

An advantage of the present invention is to provide a jig for washing analignment film printing mask that can minimize space for washing theprinting mask and improve the washing performance, and a method forfabricating a display device using the same.

Additional advantages and features of the invention will be set forth inpart in the description which follows and in part will become apparentto those having ordinary skill in the art upon examination of thefollowing or may be learned from practice of the invention. These andother advantages of the invention may be realized and attained by thestructure particularly pointed out in the written description and claimshereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purposeof the invention, as embodied and broadly described herein, a method forfabricating a liquid crystal display includes providing a firstsubstrate and a second substrate; forming an alignment layer on one ofthe first and second substrates using a mask; cleaning the mask using ajig, wherein the jig includes: a plurality of supporting members eachhaving at least one bent portion, arranged at regular intervals along awidth direction of the mask for supporting the mask; at least oneconnection member for connecting the supporting members; and fasteningunit for securing the mask supported by the supporting members;providing liquid crystal on the alignment layer; and bonding the firstand second substrates to each other.

In another aspect of the present invention, an apparatus for washing amask includes a jig for mounting a mask folded at least once; a washingunit filled with a washing solution for washing the mask; and a dryingunit supplied with a drying gas for drying the mask.

In yet another aspect of the present invention, a method for washing analignment film printing mask includes mounting an alignment filmprinting mask on a jig; dipping the jig in NMP held in a first washingunit after washing PI on the alignment film printing mask; dipping thejig in IPA held in a second washing unit to wash NMP formed on thealignment film printing mask at the time the PI is washed off in thefirst washing unit; drying the alignment film printing mask washed inthe second washing unit; and taking out the jig after said drying.

It is to be understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the invention andtogether with the description serve to explain the principle of theinvention.

In the drawings:

FIG. 1 illustrates a perspective view of a jig for an alignment filmprinting mask according to an embodiment of the present invention;

FIG. 2 illustrates a side view of the jig illustrated in FIG. 1;

FIG. 3 illustrates a perspective view of a jig for an alignment filmprinting mask according to another embodiment of the present invention;

FIG. 4 illustrates a side view of a jig for an alignment film printingmask and a transfer unit according to another embodiment of the presentinvention;

FIG. 5 illustrates a method for washing an alignment film printing maskusing a jig according to the present invention; and

FIG. 6 illustrates a flow chart illustrating the steps of a method forwashing an alignment film printing mask using an alignment film printingmask according to the present invention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Reference will now be made in detail to embodiments of the presentinvention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts.

FIG. 1 illustrates a perspective view of a jig for an alignment filmprinting mask according to an embodiment of the present invention andFIG. 2 illustrates a side view of the jig illustrated in FIG. 1.

Referring to FIGS. 1 and 2, the jig 100 includes a plurality ofsupporting members 110, at least one connection member and fasteningunits. The supporting members 110 support one side (non-active side) ofan alignment film printing mask (hereafter referred to as “mask”). Eachof the supporting members 110 is bent in a ‘U’ shape, with two endsfacing downward with respect to a center portion, and the supportingmembers 110 are mounted at regular intervals along a width direction ofthe mask 10.

The supporting members 110 are constructed of a hollow circular pipe inthis embodiment. However, the supporting members 110 may be constructedof any one of a circular pin, a polygonal bar and a hollow polygonalpipe. The center portions of the supporting members 110 are curved toprevent the mask 10 from crumpling and to be in a close contact with themask 10. The supporting members 110 are arranged at intervals in whichno crumpling of the mask 10 occurs and a washing area of the mask 10 canbe maximized. The supporting members 110 are also positioned to supportportions of the mask 10 that do not have any pattern formed thereon.

The jig 100 further includes at least one connection member 120 which isconnected to the supporting members 110. As illustrated in the drawings,the connection member 120 is mounted perpendicular to the supportingmembers 110, and crossing portions between the supporting members 110and the connection member 120 are not projected toward a side where themask 10 is positioned to prevent the mask 10 from forming a gap with thejig 100. That is, the connection member 120 crosses an inside surface ofthe supporting members 110.

Fastening units 130 secure the mask 10 supported by the supportingmembers 110 and are mounted at a bottom portion of the jig 100. Thefastening units 130 include clamps that contact and hold the mask 10 toprevent the mask 10 suffering from damage and to securely fasten themask 10. Each of the fastening units 130 includes a bolt 131, and a jaw132 for contacting and holding the mask 10, as the bolt 131 is fastened.Other fastening mechanisms, such as a general clamp in which an elasticforce of a spring is used, can be adapted to secure the mask 10.

The jig 100 is configured such that it can be automatically conveyed bya conveyance device, such as a robot arm, or it can be handled by anoperator if required. Accordingly, there are additional handlingportions 140 on the two supporting members 111 and 112 at the outermostsides of the jig 100. The handling portions 140 are connected to the twosupporting members 111 and 112, and each has the same shape as thesupporting members 110, but the width and height of the handlingportions 140 are greater than the supporting members 110. The handlingportions 140 serve not only as a hand grip for carrying the jig 100, butalso as a guide for accurately placing the mask 10 on the supportingmembers 110.

A series of steps for placing the mask 10 on the jig 100 will now bedescribed. A center of the folded mask 10 is positioned at the centersof the supporting members 110, and the two sides of the mask 10 are inclose contact with the two sides of each supporting member 110. Thus,the center of the folded mask 10 is in close contact with an outsidesurface of the centers of the supporting members 110, and the two sidesof the folded mask 10 are in close contact with outside surfaces of thetwo sides of each supporting member 110. Placing the mask 10 on the jig100 is completed by fastening the two ends of the mask 10 to thefastening units 130.

Although the two ends of the mask 10 are fastened by the fastening units130, the mask 10 can move in a width direction. Therefore, an additionalstructure is beneficially provided to prevent the mask 10 from fallingoff the jig 100 in an outer side direction of the jig 100.

Referring to FIG. 3, a jig 100 according to the present inventionincludes preventing units 141 at the outermost supporting members 111and 112 to prevent the mask 10 from falling off the jig 100 in an outerside direction. The two ends of each preventing unit 141 connect the twosides of the outermost supporting member 111 or 112. Each preventingunit 141 may include a clamp identical to the fastening portion 130 tosecure the two sides of the mask 10. An outer frame 105 supports thesupporting members 110, outermost supporting members 111 or 112, andconnection member 120.

Referring to FIG. 5, a transfer unit 150 on a underside (morespecifically, opposite undersides of the supporting members) may be usedto easily carry the jig 100 toward a washing apparatus. Accordingly, thetransfer unit 150 includes a body 151 having a upper surface contactingthe two ends of each supporting member 110, and rollers 152 on aunderside of the body 151. Particularly, each supporting member 110 isdetachable from the transfer unit 150. That is, when the mask 10 isintroduced into a washing apparatus, the transfer unit 150 is detachedso that only the mask 10 mounted on the jig 100 is introduced into thewashing apparatus. The jig 100 may be conveyed to the washing apparatusby a robot arm.

FIG. 5 illustrates a method for washing an alignment film printing maskusing a jig according to the present invention.

Referring to FIG. 5, the washing apparatus includes a jig 100, a washingunit 200 and a drying unit 300. As described above, the jig 100 isconfigured such that a mask 10 folded in half are mounted thereon.

The washing unit 200 filled with a washing solution has enough space tofully submerge the jig 100 to clean the mask 10. The washing unit 200includes at least one PI (polyimide) washers 210 and at least one NMPwasher 220. There are two PI washers 210, and a space between the two PIwashers 211 and 212 is partitioned. Each of the two PI washers 211 and212 holds NMP (N-Methyl Pyrrolidone) for washing PI remains on the mask10.

The first PI washer 211 into which the jig 100 is first introduced(hereafter referred to as “primary PI washer”) includes a bubblegenerating portion 230 for generating bubbles and providing the bubblesto NMP held therein. The bubbles cause NMP to circulate so that anentire portion of the mask 10 can be uniformly washed. Although notshown, the bubble generating portion 230 generates bubbles by injectinga gas. The second PI washer 212 (hereafter referred to as “secondary PIwasher”) receives the mask 10 washed at the primary PI washer 211 andwashes the mask 10 again.

An NMP washer 220 holding IPA (Iso Propyl Alcohol) therein receives themask 10 washed in succession at the two PI washers 211 and 212 andwashes off the NMP remains on the mask 10 with IPA. The washing unit 200may further include a separate DI holding tank 240 holding deionizedwater.

The drying unit 300 dries the washed mask 10 and has enough space tofully hold the jig 100. A drying gas is supplied to the drying unit 300to dry the mask 10. There is a nozzle 320 connected to the drying unit300 to supply the drying gas from a gas storage unit 310. The gas isgenerally N₂ gas. The washing apparatus may have the washing unit 200and the drying unit 300 separate from each other, or may be formed as asingle unit as illustrated in FIG. 5.

A series of steps for washing and drying the mask 10 will now bedescribed with reference to FIG. 6.

First, the mask 10 is mounted on the jig 100 (S110). The jig 100 withthe mask 10 mounted thereon is then conveyed to the primary PI washer211. The jig 100 may be conveyed by the transfer unit 150. The jig 100conveyed to the primary PI washer 211 is then separated from thetransfer unit 150, and is introduced into the primary PI washer 211(S120). NMP held in the primary PI washer 211 washes PI off a surfaceand openings (not shown) of the mask 10 mounted on the jig 100. Asdescribed above, bubbles generated from the generating portion 230 flowin the primary PI washer 211 to uniformly deliver NMP to variousportions of the mask 10.

The mask 10 finished at the primary PI washer 211 is taken out of theprimary PI washer 211 and introduced into the secondary PI washer 212,together with the jig 100 (S130). The PI remains on the mask 10 iswashed again by NMP held in the secondary PI washer 212. NMP in thesecondary PI washer 212 is cleaner than NMP in the primary PI washer211. Therefore, as the mask 10 passes successively through the primaryPI washer 211 and the secondary PI washer 212, the PI remains at thesurface and openings of the mask 10 is completely removed.

The mask 10 finished at the secondary PI washer 212 is then taken out ofthe secondary PI washer 212 and introduced into the NMP washer 220,together with the jig 100 (S150). The mask 10 may be briefly introducedinto a separate DI holding tank 240 holding deionized water therein(S140) before the mask 10 is introduced into the NMP washer 220. IPAheld in the NMP washer 220 washes NMP remains introduced by the NMPwasher 220 off the mask 10.

Then, the mask 10 finished at the NMP washer 220 is taken out of the NMPwasher 220 and introduced into the drying unit 300, together with thejig 100 (S160). The nozzle 320 connected to the drying unit 300 providesN₂ gas from the gas storage unit 310 to the drying unit 300 to dry themask 10. Although the mask 10 is mounted on the jig 100, N₂ gas isuniformly provided to both sides (an active side, and a non-active side)of the mask 10 because sides of the jig 100 are open. After drying themask 10, the jig 100 is then taken out of the drying unit 300 (S170) anddischarged from the washing apparatus, thereby completing the washingprocess of the mask 10.

The jig 100 of the present invention is not limited to the structuresdescribed in the foregoing embodiments. Each of the supporting members110 of the jig 100 may have at least two bent portions to decrease theheight of the washing apparatus 200 (or the jig 100). That is, becausethe mask 10 has a height in a range of 2000 mm˜3000 mm, the centerportion of the mask 10 is folded once in the earlier description.However, when the mask 10 has a size greater than 3000 mm, the mask 10may be folded at least two times. In such a case, bending is made in adirection opposite each other. In addition, a bent portion of eachsupporting member 110 may further include an additional structure toprecisely place the mask 10 close to the bent portion.

The forgoing embodiments of the present invention disclose a circularbent portion of each the supporting members 110. However, although notshown, the bent portion may be polygonal. Also, the bent portion may becurved such that the bent portion is in contact with the mask 10.

The forgoing embodiments of the present invention disclose that the twosides of each supporting member 110 are parallel to each other. However,the two sides of each supporting member 110 may be formed to come closeror to move away from each other as it goes toward a bottom portionthereof.

As described above, a jig according to the present invention can hold analignment film printing mask that is folded at least once, therebyminimizing space and the consumption of NMP or IPA required for washingthe mask.

Moreover, a jig according to the present invention increases the washingefficiency because the transfer unit detachable from the supportingmembers is used to convey the mask to a washing apparatus, and becauseonly the jig excluding the transfer unit is introduced into the washingapparatus.

An apparatus and method for washing an alignment film printing maskaccording to the present invention removes polyimide remains on the maskmore completely and dries the mask more uniformly.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present invention. Thus,it is intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. An apparatus for washing a mask comprising: a jig for mounting a mask folded at least once; a washing unit filled with a washing solution for washing the mask; and a drying unit supplied with a drying gas for drying the mask, wherein the jig includes: a plurality of supporting members each having at least one bent portion, arranged at regular intervals along a width direction of the mask for supporting the mask draped vertically over the bent portions; at least one connection member for connecting the supporting members; and fastening units for securing the mask supported by the supporting members.
 2. The apparatus as claimed in claim 1, wherein the washing unit includes; at least one first washing part having NMP (N-Methyl Pyrrolidone) held therein for washing polyimide remains off the mask, and at least one second washing part having IPA (Iso Propyl Alcohol) held therein for receiving the mask washed at the first washing part and washing N-Methyl Pyrrolidone off the mask.
 3. The apparatus as claimed in claim 2, wherein the first washing part includes first and second polyimide washers, the first polyimide washer including a bubble generating portion for generating bubbles and providing the bubbles to N-Methyl Pyrrolidone held therein.
 4. The apparatus as claimed in claim 1, wherein the drying gas is N₂ gas.
 5. The apparatus as claimed in claim 1, wherein the washing unit has enough space to fully submerge the jig.
 6. The apparatus as claimed in claim 1, wherein the washing unit further includes a separate DI holding tank holding deionized water.
 7. The apparatus as claimed in claim 1, wherein the drying unit has enough space to fully put in the jig.
 8. The apparatus as claimed in claim 1, wherein each of the supporting members has two ends facing downward with respect to a center portion.
 9. The apparatus as claimed in claim 1, wherein each of the supporting members has at least two bent portions in a direction opposite to each other.
 10. The apparatus as claimed in claim 1, wherein each of the supporting members is constructed of one of a circular pin, a polygonal bar, a hollow circular pipe and a hollow polygonal pipe.
 11. The apparatus as claimed in claim 1, wherein the bent portion of the supporting member is curved.
 12. The apparatus as claimed in claim 1, wherein the interval between the supporting members is set so that no crumpling of the mask occurs, and smooth washing of the mask can be achieved.
 13. The apparatus as claimed in claim 1, wherein the supporting members are arranged to support the mask at portions of the mask where the patterns for printing an alignment film on a substrate are not formed thereon.
 14. The apparatus as claimed in claim 1, wherein portions of the supporting members crossing the connection member have no projection toward a side the mask is to be positioned.
 15. The apparatus as claimed in claim 1, wherein the fastening units are mounted to the supporting members.
 16. The apparatus as claimed in claim 15, wherein the fastening unit is a clamp for making a surface to surface contact with, and fastening the mask.
 17. The apparatus as claimed in claim 1, further comprising preventing units at the outermost two supporting members for preventing the mask supported by the supporting members from falling off toward an outer side direction.
 18. The apparatus as claimed in claim 17, wherein the preventing unit has two ends connected to the outermost supporting member.
 19. The apparatus as claimed in claim 1, further comprising a transfer unit on the jig.
 20. The apparatus as claimed in claim 19, wherein the transfer unit includes; a body having a upper surface for coupling to the jig, and rollers on a underside of the body for moving the jig.
 21. The apparatus as claimed in claim 20, wherein the jig is detachable from the body.
 22. The apparatus as claimed in claim 1, wherein the mask is a mask for forming an alignment film. 